These tools are required to be able to login and use your system. The
login program invokes your user shell and enables command execution. The
newgrp program is used to change your effective group ID (useful for
workgroup type situations). The su program allows changing your effective
user ID (useful being able to execute commands as another user).

/usr/share/doc/login/NEWS.gz

$Id: NEWS 1958 2008-04-02 21:55:27Z nekral-guest $
shadow-4.1.0 -> shadow-4.1.1 02-04-2008
*** general:
- security
* Do not seed the random number generator each time, and use the time in
microseconds to avoid having the same salt for different passwords
generated in the same second.
- packaging
* Do not install the shadow library per default.
- general
* Do not translate the
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